In recent years, the development of the computer technology has been remarkable and products with a variety of functions have been materialized as application of the computer technology. This trend of the industry has brought about increasing requirements for the various sensors of a higher performance to work together with computers. The applications of angular rate sensors cover such areas as the automobile navigation system utilizing a angular velocity component detected by the sensor, the direction detector in robots, the stabilizer in various driving mechanisms and the like. The angular rate sensor with such applications tends to require compactness and high performance to serve its purposes. So far, the inertial navigation equipment of gyroscopes has been mainly used in finding a moving direction of vehicles such as airplanes and ships. This inertial navigation equipment is reliable enough in direction finding, but it is big and expensive because it is a mechanical system, making it difficult to use in the consumer electronic equipment which usually requires decreasing sizes. On the other hand, there is the oscillating gyro under proposal (Japanese Patent Application Number S-59-55420), which utilizes a vibrating mass instead of a rotating motion to detect an angular rate, derived from the so-called Coriolis force of the vibrating mass. The oscillating gyro can be considered as an oscillating sensor of a tuning fork structure. It is composed of two rectangular plates of an elastic element, the one of which is for driving as a tuning fork and the other of which is for detecting angular rates. The two plates are longitudinally aligned and joined end to end, yet being twisted 90.degree. with each other. Thus, the Coriolis force is detected from the detecting elastic element with a velocity (m/s) which is generated by the turning fork vibration. An explanation on the conventional angular rate sensor will be given in the following with a help of a drawing: FIG. 7 shows a block diagram inclusive of the angular rate sensor and its driving circuits. Each of the driving piezoelectric bimorph elements 103 and 104 working as the driving elastic element is joined end to end by the connecting means 105 and 106 with each of the detecting piezoelectric bimorph elements 101 and 102 working as a detecting elastic element, and aligned longitudinally along the detecting axes of thedetecting piezoelectric bimorph elements 101 and 102 and also positioned with the respective vibrating axes rectangularly crossing. The pair of bimorph element structure thus constructed is then joined by the supporting member 107 at the one end of the respective driving piezoelectric bimorph elements 103 and 104, completing a vibrating set-up. This vibrating set-up is supported and connected as well through a metal elastic element 108 by and to the base 109. Tuning fork vibrations of the vibrating set-up take place when driving the driving piezoelectric bimorph elements 103 and 104. When an angular rate is applied to the detecting piezoelectric bimorph elements of the vibrating set-up, 101 and 102, an angular rate output is obtained from the detecting piezoelectric bimorph elements 101 and 102. A detailed explanation on the operation of the above whole set-up will follow: A drive signal supplied from the driving circuit 110 to the driving piezoelectric bimorph element 103 will activate the driving piezoelectric bimorph element 104 to a resonating vibration. A feedback loop is formed by connecting the driving circuit 110, the automatic gain control circuit (AGC circuit) 111, the driving monitor 113 and the driving piezoelectric bimorph elements 104 and 103 to start a tuning fork vibration. The amplitude signal gained from the driving bimorph element 104 is fedback to the driving circuit 110 after the AGC circuit 111, keeping the amplitude of the tuning fork vibration constant. By taking out a part of the phase signal information of the detecting signal generated in the driving piezoelectric bimorph by the driving monitor 113, a DC detect signal corresponding to the angular rate detected after the rectifying circuit 115 and the filter circuit 116 for low pass filtering is outputted from the angular rate signal component obtained at the detecting piezoelectoric bimorph elements 101 and 102. Incidentally, when the angular rate sensor of this kind is subjected to a temperature change, a pyroelectric effect caused by the polarization magnitude changes corresponding to the temperature change rate will be brought about with a resultant application of a self bias voltage to the piezoelectric bimorph. This self bias voltage is caused by changing increment of the surface electric charges generated in the piezoelectric bimorph element. The self bias voltage causes a large fluctuation in the detecting information signal (off-set voltage) of the angular rate sensor. Although the temperature change magnitude may be the same, a smaller variation in the off-set voltage of the angular rate detecting signal is observed with an application of mildly changing temperature, whereas the off-set voltage changes greatly with an application of temperature changing by steps. In other words, the temperature drift characteristic changes in off-set voltage) which makes one of the important performance factors for an angular rate sensor, is greatly affected by the pyroelectric effect of the piezoelectric vibrators composed of piezoelectric bimorph elements. With the conventional tuning fork type angular rate sensors of piezoelectric vibrators that comprise piezoelectric bimorph elements, the temperature drift is caused by the adverse effect of the thermal expansion particular to the piezoelectric vibrators and the foregoing pyro-electric effect. Therefore, an application of a far infrared radiation or a temperature change to the piezoelectric vibrators which are inherently vulnerable will generate an electromotive force. In other words, just because of this temperature drift, the conventional vibration type angular rate sensors such as the tuning fork type and the like have the limitation as an high precision sensor and it has been considered difficult to improve them to highly precise sensors.